题目

某太阳能热水器中装有质量50千克的水，在阳光的照射下，该热水器中水的温度从25℃升高到65℃，求这些水吸收的热量？[c水=4.2×103J/（kg•℃）]． 答案：解：水吸收的热量： Q吸=cm（t﹣t0） =4.2×103J/（kg•℃）×50kg×（65℃﹣25℃） =8.4×106J． 答：水吸收的热量是8.4×106J．Air is a colorless, tasteless and invisible（看不见的）gas that is around us. An “empty” drinking glass and an “empty” room, in fact, are not really empty. Each is filled with air. When the glass is filled with water, the water pushes the air out of the glass.Air, as a gas, has no definite shape, but because it is matter, it takes up space and it has weight. It is easy to prove that air is something that takes up space. Stuff a piece of dry cloth（布）into the bottom of a glass so that it will not fall out when the glass is turned upside down. Push the upside down glass, holding straight up and down, into a jar of water till the glass is completely covered. When the glass is taken out of the water, the cloth is still dry. The air inside the glass shows that it takes up space and keeps the water from coming in.小题1:Since air is matter, it has ________.A．room , and weight as wellB．both room and shapeC．either room or weightD．neither shape nor weight小题2:The word “Stuff” means ______ in Chinese. A．撕B．盖C．取掉D．塞小题3:The writer tells that the experiment（实验）___________.A．is carried out in the spaceB．must be done in the labC．is made in the roomD．can only be done in the open air